1. Field of the Invention
The invention pertains to microwave power semiconductor devices. More particularly, the invention relates to avalanche-type microwave power diodes with improved thermal properties.
2. Description of the Prior Art
Gallium arsenide IMPATT type diodes have recently been developed for use as oscillators in the C and X microwave bands. Efficiencies on the order of 25% to 30% have been found possible for Read-type IMPATT diodes. It has been the practice to mount single-mesa devices upon a single heat sink for most oscillator applications. Power output in such devices has been limited to typically five watts because of the upper limit upon allowable junction temperatures for practical diode chip sizes. For many applications, such as in radars and in communications, a higher power level has been desired. In double-drift type avalanche diodes in which the junction is formed substantially in the center of the semiconductor body relatively far from the heat sink surface, the problem is further exasperated because most of the heat in such a device is generated in the region of the junction and must subsequently flow through long distances of semiconductor material.